Transparent fibre channel concentrator for point to point technologies

ABSTRACT

A data processing system for transferring data from a first plurality of data links to a second plurality of data links is provided. A data bridge is initialized. The data bridge is functionally connected on a first end to the first plurality of data links and on a second end to the second plurality of data links. A determination is made if a first data link within the first plurality of data links and a second data link within the second plurality of data links initiate a login parameter. Data is automatically transferred from a source data link within the first plurality of data links to a target data link within the second plurality of data links based on the login parameter.

1. TECHNICAL FIELD

[0001] The present invention is directed to a path balancing apparatusand method. In particular, the present invention is directed to anapparatus and method for multiplexing along multiple communication pathsto a plurality of devices. Still more particularly, the presentinvention is directed to an apparatus and method for multiplexing alongmultiple communication paths to a plurality of devices without anexternal switching device.

2. DESCRIPTION OF RELATED ART

[0002] With the relatively high costs of a Fibre Channel data path, itis important to use as much of the available path bandwidth as possible.Currently, in many user environments, the data path may be underutilizedwith a single Fibre Channel (FC) port. One way to mitigate the costs ofthe data path is to provide connectivity for more than a single FC portso that the power of the data path may be fully utilized. If data pathsare shared by FC ports with small incremental cost additions and nosignificant reduction in performance, the user may see greaterhost/device connectivity at a lower cost per port. Therefore, it wouldbe advantageous to have an apparatus and method for sharing a data pathbetween multiple FC ports.

SUMMARY OF THE INVENTION

[0003] The present invention provides a data processing system fortransferring data from a first plurality of host data links to at leasta single local data link. A data bridge is initialized. The data bridgeis functionally connected on a first end to the first plurality of datalinks and on a second end to the second plurality of data links. Adetermination is made if a first data link within the first plurality ofdata links and a second data link within the second plurality of datalinks initiate a login parameter. Data is automatically transferred froma source data link within the first plurality of data links to a targetdata link within the second plurality of data links based on the loginparameter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The novel features believed characteristic of the invention areset forth in the appended claims. The invention itself, however, as wellas a preferred mode of use, further objectives and advantages thereof,will best be understood by reference to the following detaileddescription of an illustrative embodiment when read in conjunction withthe accompanying drawings, wherein:

[0005]FIG. 1 is an exemplary block diagram of connectivity for more thana single FC port in accordance with a preferred embodiment of thepresent invention;

[0006]FIG. 2 is an exemplary block diagram of a single port PCImezzanine FC board is illustrated in accordance with a preferredembodiment of the present invention;

[0007]FIG. 3 is an exemplary block diagram of a class 3 login frameexchange between a host and the local FC port utilizing a fibre channelconcentrator PCI mezzanine board in accordance with a preferredembodiment of the present invention;

[0008]FIG. 4 is an exemplary high level block diagram of a fibre channelconcentrator integrated circuit hardware in accordance with a preferredembodiment of the present invention;

[0009]FIG. 5 is an exemplary flow diagram describing the states of fibrechannel concentrator main state machine during the link initializationprocess in accordance with a preferred embodiment of the presentinvention;

[0010]FIG. 6 is an exemplary flow diagram describing the logininitialization during a main active state in accordance with a preferredembodiment of the present invention; and

[0011]FIG. 7 is an exemplary flow diagram describing the reception of afabric login frame when the fibre channel concentrator is not in thelogin lockout state in accordance with a preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0012] The present invention provides an apparatus and method by whichto directly connect a plurality of hosts to a single fibre channel (FC)link without the need of an external switch. This provides connectivitybenefits in which the hosts are using only a portion of the linkbandwidth. Hardware may be used to allow the hosts to transparentlyshare the FC link into an FC controller. This hardware may acts as a FCframe multiplexer/demultiplexer with buffering capability. Receiveframes from the plurality of external ports are multiplexed onto thelocal FC link. Transmit frames on the local FC link are routed by adestination identifier (ID) to one of the external ports.

[0013]FIG. 1 is an exemplary block diagram of connectivity for more thana single FC port in accordance with a preferred embodiment of thepresent invention. A solution to mitigation of the costs of the datapath is to provide connectivity for more than a single FC port so thatthe power of the data path may be fully utilized. If data paths areshared by FC ports with small incremental costs additions and nosignificant reduction in performance, a greater host/device connectivitymay be provided which results in a lower cost per FC port. Therefore, inthis example, concentrator 100 merges FC point to point physical links102 into a single FC link 104 by the processes of the present invention.

[0014]FIG. 2 is an exemplary block diagram of a single port PCImezzanine FC board is illustrated in accordance with a preferredembodiment of the present invention. FIG. 2 provides further detail ofFIG. 1. Concentrator device 202 may have several improvedcharacteristics over the prior art. For example, concentrator device 202may be transparent to external FC hosts/devices, require little or nomanagement, data need only flow between the host port(s) and the localFC port and may support class 2 and class 3 frame exchanges.Concentrator 202 acts as a physical layer end-point and provides abridging function to move frames between external links and local links.

[0015] In this example, concentrator 202 may consist of a local FC port204 and a plurality of host ports 206. One local port is shown in thisexample but any number of local ports may be employed in accordance witha preferred embodiment of the present invention. In addition, three hostports are shown in this example but any number of host ports may beemployed in accordance with a preferred embodiment of the presentinvention. Furthermore, concentrator 202 may also consist of bufferdirect memory access (DMA) controller 208.

[0016] Concentrator 202 may achieve a variety of states during the firststage of an initialization process, such as, for example,

[0017] a. main_reset: the main_reset state may be entered at power-up orif both the local link and all of the external links have gone to anoffline state. In the main-reset state, all of the links may be forcedoffline. Concentrator 202 then monitors an incoming signal from thelinks and if a local link and one or more of the external links havereceived a valid FC primitive sequence, the internal state ofconcentrator 202 advances to a main-online state.

[0018] b. main_online: the main_online state turns on all of the locallinks and external links if the links have received a valid primitivesequence and allowed to progress through a FC link state initializationprotocol until the link is in an active state.

[0019] c. main_active: the main_active state is the normal activeoperating state. In the main_active state frame traffic may occur.

[0020] d. main_offline: the main_offline state occurs in concentrator202 if a local link or all of the external links drop out of themain_active state at any time. While in the main_offline state, all ofthe active links are forced offline. When each link completes theoffline protocol, concentrator 202 returns to the main-reset state inorder to reinitialize the links.

[0021] The achievement of the variety of states during the first stageof an initialization process is further illustrated in FIG. 5.

[0022] After the main_active state is achieved, FC endpoints (hosts andlocal links) initiate fabric login and port login in order to passoperating parameters. The initiation of fabric login and port login isimportant to concentrator 202 because buffer credits and portidentification are established during the fabric and port logins.Special states are entered when fabric and port login frames aredetected. An example of these special states is:

[0023] main-flogi (fabric login): Concentrator 202 enters this specialstate when a fabric login frame is received from an external link. Whilein this state, and main_plogi described below, only frames received fromthe same link as the fabric login are forwarded to the local link.Frames received from other external links are held in buffers, such as,for example, buffer RAM 210 until the login lockout is complete. Anylogin type frames, for example, flogi, plogi or acc (login acknowledge)received from the local link are forwarded to the initiating fabriclogin external link. Any other frames received from the local link areforwarded to the appropriate external link as indicated by the locallink's destination identifier.

[0024] main_plogi (main port login): The main plogi state is acontinuation of the login process. The main_plogi state is entered whena port login frame is received from an external link. When a loginacknowledge (acc) is received from the local link, the login process iscomplete and concentrator 202 returns to the main_active state. Thedestination identifier field of the acc (N-port parameters) is capturedand used to compare with the destination identifier of subsequent framesto determine which external link to route outbound frames from the locallink.

[0025] The process of entering the special states when fabric and portlogin frames are detected is further illustrated in FIG. 6.

[0026] However, a condition may arise in which a fabric login isreceived from a local link and concentrator 202 is not in a loginlockout state. This scenario is possible if the local link is the firstto attempt a fabric login after initialization. If the destinationidentifier from the local link is a valid match for one of the externallinks, the frame is forwarded to the associated external link.Otherwise, if the destination identifier is not a valid match for one ofthe external links, the frame may be held in buffer RAM 210 byconcentrator 202 until the login lockout states are properly entered dueto a login initiated by an external state, at which point the frame isforwarded to the external link. This process is further explained inFIG. 7.

[0027] Data is routed through concentrator 202. In particular,concentrator 202 receives data from a variety of sources, which may befrom, for example, a local link consisting of FC transceiver 216 andoptical transceiver 218 or from a plurality of external links. In thisexample, optical transceivers 220, 222 and 224 in conjunction with quadFC transceiver 214 comprise the external links. The process of bringingexternal FC links and the local FC link from a power-up or reset stateto receiving active data traffic may involve two main milestones. First,the local links and at least one external link may be brought to theactive state. Then the local links and the external link ports completethe fabric login protocols and the port login protocols, which definethe port identification (ID) and allow concentrator 202 hardware todirect frames to the proper external FC link destination.

[0028] Reference oscillator 212 provides a clock signal for the inputand output of the data. Data received by concentrator 202 may send thedata directly from local port 204 to host port(s) 206 through buffer DMAcontroller 208 or may store the data in buffer ram 210 via data link236. In addition, control signal 232 and address signal 234 flows frombuffer DMA controller 208 and buffer RAM 210. The present invention, asillustrated in FIG. 2, is not confined to providing data in only onedirection. In other words, quad transceiver 214 may either output datato concentrator 202 or input data from concentrator 202. Likewise, FCtransceiver 216 may either output data to concentrator 202 or input datafrom concentrator 202.

[0029] The operation of concentrator 202 is as follows. Opticaltransceivers, such as for example, optical transceivers 220, 222 and 224may provide input into quad FC transceiver 214. Furthermore, quad FCtransceiver 214 may accept input from reference oscillator (OSC) 212.Quad FC transceiver 214 takes the input from optical transceivers 220,222 and 224 as well as the input from reference OSC 212 and in turnprovides input into concentrator 202 via host port(s) 206. In turn, hostport(s) 206 send the inputted data to buffer DMA controller 208. BufferDMA controller 208 receives the data and sends the data to buffer RAM210 for temporary storage. All received data passes through buffer RAM210. Buffer RAM 210 is used to store data frames received on the links.Data is held in buffer RAM 210 until the frame is transmitted by one ofthe FC links. Although buffer RAM 210 supports bi-directional data, thisimplementation uses one of the data busses to write data and the otherfor read data so the data movement is unidirectional.

[0030] Data comes from host port 206 via both buffer DMA controller 208as well as buffer RAM 210, and is then sent to local port 204. In oneembodiment, local port 204 receives data from and transmits data to FCtransceiver 216, which in turn transmits the data to optical transceiver218. In another embodiment, local port 204 transmits data to andreceives data from local FC controller 226, which in turn transmits datato and receives data from PCI bus interface 229. Local FC controller 226receives control input 228 and address/data input 230 through PCI businterface 229 and provides control input 228 to concentrator 202.

[0031]FIG. 3 is an exemplary block diagram of a class 3login frameexchange between a host and local port utilizing a fibre channelconcentrator PCI mezzanine board in accordance with a preferredembodiment of the present invention. FIG. 3 illustrates class 3 loginframe exchanges between host port 302 and local port 306 withconcentrator 304 between host port 302 and local port 306.

[0032] In this example, main_active state transitions are illustrated.Concentrator 304 consists of external link port (EL) 308 and local linkport (LL) 310. Link endpoint concentrator 304 is involved in buffer tobuffer flow control across external link 308 and local link 310.However, concentrator 304 may not be involved in end to end flowcontrol, therefore, acc frames may be forwarded in a similar manner asany other frame. Concentrator 304 monitors for login frames such aslogin frames 312 and 324 and captures remote buffer to buffer creditparameters for each link as the link is logged in. When the link isreset, the remote credit for each link is set to a value of 1. SeparateBuffer-to-Buffer (BB) credit counters are maintained for each link andframes and are transmitted only if the BB credit count is less than theremote buffer to buffer credit parameter.

[0033]FIG. 4 is an exemplary high level block diagram of a fibre channelconcentrator integrated circuit hardware in accordance with a preferredembodiment of the present invention. In this example, within the fibrechannel concentrator 202 in FIG. 2 are four independent FC link datapaths 432 a/434 a, 432 b/434 b, 432 c/434 c and 432 d/434 d withindependent link state machines 422 a, 422 b, 422 c and 422 d,respectively. Link state machines 422 a, 422 b, 422 c and 422 d mayprovide output to buffer memory control block 420. In addition, thereare separate blocks for main state machine 402, buffermanagement/forwarder 426, frame cracking header 404 and controlinterface 406.

[0034] In this example, FC link interface blocks 401 a, 401 b, 401 c and401 d within concentrator 202 in FIG. 2 may be identical. Each linkinterface 401 a, 401 b, 401 c and 401 d may be divided into, forexample, three main functions. For example, receive data path 434 a,transmit data path 432 a and link state machine 422 a comprise linkinterface 401 a. Data paths 432 a and 434 a may be independent andunidirectional. Flow control information may be passed between the datapaths. Link state machine 422 a may be used to execute linkinitialization and error recovery protocols.

[0035] Link state machines 422 a, 422 b, 422 c and 422 d execute thelink initialization and error recovery protocols. Link state machines422 a, 422 b, 422 c and 422 d monitor the primitive sequences detectedby a receive data path, for example receive data path 434 a, to generateordered sets based on the current link state. Frame buffer SRAMcontroller 420 controls access to an external frame buffer synchronousSRAM via write data path 412, address path 414 and read data path 416.Frame buffer SRAM controller 420 accepts separate buffer address fromtransmit and receive data paths from FC links 401 a, 401 b, 401 c and401 d, as well as write data from each receive data path. Each data pathmay be guaranteed one-fourth of the total access bandwidth. Anacknowledge message is passed to each data path to enable dataread/write from a FIFO's and address increment.

[0036] Buffer management/forwarder 426 maintains the buffer queues foreach of the FC links. Buffer management/forwarder 426 communicates totransmit data paths 432 a, 432 b, 432 c and 432 d as to where thetransmit data paths' next transmit buffer is located and communicates toreceive data paths 434 a, 434 b, 434 c and 434 d where to store incomingframes. Buffer management/forwarder 426 directs the forwarding ofreceived frames to the proper transmitter based on the input from frameheader rack 404.

[0037] Frame header crack 404 examines the contents of each frametransmitted and received from a local port. Frame header crack 404specifically checks for FLOGI and PLOGI frames and the corresponding ACKframes which may be used for special login sequences. Frame header crack404 extracts BB credit parameters from the frames during initializationand passes the BB credit parameters to the individual FC linkcontrollers. Frame header crack 404 also captures during login thedestination ID of the external link so that when normal frames arereceived from the local link the identifier can be compared and theframe forwarded to the proper destination.

[0038] Main state machine 402 coordinates the initialization ofconcentrator 202 as a whole, including reset, online/offline enabling,and special login sequences. Main state machine 402 monitors theindividual link states and receives input from frame header crack 404.Control interface 406 supports external I2C interface 408 protocolallowing access to internal registers and status.

[0039]FIG. 5 is an exemplary flow diagram describing the states of fibrechannel concentrator main state machine during the link initializationprocess in accordance with a preferred embodiment of the presentinvention. In this example, the operation starts with powering up thesystem (step 502). The main_reset state is entered (step 504) and then adetermination is made as to whether or not both local links and externallinks are offline (step 506). If both local links and external links arein the offline state (step 506:YES), the links are forced offline (step508) and the operation returns to step 504 where the main_reset state isentered. If both the local link and the external links are not in theoffline state (step 506:NO), the incoming signal is monitored (step510). Then a determination is made as to whether or not the local linksand one or more external links are alive (step 512). If the local linkand one or more external links are not alive (step 512:NO), theoperation returns to step 510 where the incoming signal is monitored.

[0040] If the local link and one or more external links are alive (step512:YES), the operation advances to the main online state (step 514).The links are turned online (step 516) and then the link stateinitialization protocol is activated (step 518). The progression throughlink state initialization protocol is allowed to proceed (step 5206).Then a determination is made as to whether or not the system is in themain_active state (step 522). If the system is not in the main_activestate (step 522:NO), the operation returns to step 520 where theprogression through the link state initialization protocol is allowed.If the system is in the main_active state (step 522:YES), the systemallows frame traffic to flow (step 524). Then a determination is made asto whether the local link or all of the external links are not active(step 526).

[0041] If the local link and one or more of the external links areactive (step 526:NO), the operation returns to step 524 where the frametraffic is allowed to flow. If the local link or all of the externallinks are not active (step 526:YES), the main_offline state is entered(step 528). The links are forced offline (step 530) and then adetermination is made as to whether or not the links have completedoffline protocol (step 532). If the links have not completed offlineprotocol (step 532:NO), the operation returns to step 530 where thelinks are forced offline. If the links have completed offline protocol(step 532:YES), the operation returns to step 504 where the main_resetstate is entered.

[0042]FIG. 6 is an exemplary flow diagram describing the logininitialization during a main active state in accordance with a preferredembodiment of the present invention. In this example, the operationbegins with a determination as to whether or not the main active statehas been achieved (step 602). If the main_active state has not beenachieved (step 602:NO), the operation performs in accordance with anyother achieved states (step 642). If the main_active state has beenachieved (step 602:YES) , fabric login is initiated (step 604). Thenport login is initiated (step 606). Then a determination is made as towhether or not fabric login and port login frames are detected (step608). If fabric login and port login frames are not detected (step608:NO), the operation continues to determine as to whether or notfabric login and port login frames have been detected (step 608). Iffabric login and port login frames have been detected (step 608:YES), adetermination is made as to whether or not a fabric login frame has beenreceived from an external link (step 610). If a fabric login frame hasnot been received from an external link (step 610:NO), the operationreturns to step 608 where a determination is made as to whether or notfabric login and port login frames have been detected.

[0043] If a fabric login frame has been received from an external link(step 610:YES), the main_flogi state is entered (step 612). Then adetermination is made as to whether or not a frame has been receivedfrom the same link as the fabric login (step 614). If a frame has notbeen received from the same link as the fabric login (step 614:NO), theframe is held in a buffer (step 616). Then a determination is made as towhether or not a login lockout is complete (step 620). If the loginlockout is not complete (step 620:NO), the operation returns to step 616where the frame is held in a buffer. If the login lockout is complete(step 620:YES), the frame is forwarded to the local link (step 618).

[0044] Returning to step 614, if the frame is received from the samelink as the fabric login (step 614:YES), the frame is forwarded to thelocal link (step 618). The frames from the local link are received (step622) and then a determination is made as to whether or not the framesare to be forwarded to the initiating fabric login external link (step626). If the frames are not to be forwarded to the initiating fabriclogin external link (step 626:NO), the frames received from the locallinks are forwarded to the appropriate external link as indicated by thedestination identifier (step 630) and thereafter the operationterminates. If the frames are to be forwarded to the initiating fabriclogin external link (step 626:YES), then the frames are forwarded to theinitiating fabric login external link (step 628) and thereafter theoperation terminates.

[0045] Returning to step 608, if the fabric login and port login framesare not detected (step 608:NO), a determination is made as to whether ornot the port login frame has been received from the external link (step632). If the port login frame has not been received from the externallink (step 632:NO), the operation returns to step 608 in which todetermine as to whether or not the fabric and port login frames havebeen detected. If the port login frame has been received from theexternal link (step 632:YES), the main_plogi state is entered (step634). Then a determination is made as to whether or not the loginacknowledge (Acc) has been received from the local link (step 636). Ifthe “Acc” has not been received from the local link (step 636:NO), theoperation returns to step 610 where a determination is made as towhether or not the port login frame has been received from the externallink. If the “Acc” has been received from the local link (step 636:YES),the destination field is captured from the login acknowledge (acc) (step638). The destination identifier is then compared with the destinationfield of subsequent frames to determine which external link to routeoutbound frames from the local link (step 640) and thereafter theoperation returns to step 604 where the fabric login is initiated.

[0046]FIG. 7 is an exemplary flow diagram describing the reception of afabric login frame when the fibre channel concentrator is not in thelogin lockout state in accordance with a preferred embodiment of thepresent invention. In this example, the operation starts with adetermination as to whether or not a frame is received from a local link(step 702). If a frame is not received from a local link (step 702:NO),the operation terminates. If a frame is received from a local link (step702:YES), a determination is made as to whether or not the system is inthe login lockout stage (step 704). If the system is not in the loginlockout stage (step 704:NO), the frame is stored and the operationreturns to step 704 to determine whether or not the system is in thelogin lockout stage. If the system is in the login lockout stage (step704:YES), a determination is made as to whether or not the destinationidentifier of the local link matches the destination identifier of theexternal link (step 706).

[0047] If the destination identifier of the local link does not matchthe destination identifier of the external link (step 706:NO), the frameis stored (step 710) and the operation returns to step 704 to determinewhether the system is in login lockout stage. If the destinationidentifier of the local link does match the destination identifier ofthe external link (step 706:YES), the frame is forwarded to theassociated external link (step 708) and thereafter the operationterminates.

[0048] Therefore, the present invention provides the ability to connecta plurality of hosts to a single fibre channel link without the need ofan external switch. This provides connectivity benefits such as, forexample, using as much of the available bandwidth as possible,mitigating the costs of the data path and no reduction in performance inwhich the user may see greater host/device connectivity at a lower costper port.

[0049] The description of the present invention has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the invention in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art. The embodiment was chosen and described in order to bestexplain the principles of the invention, the practical application, andto enable others of ordinary skill in the art to understand theinvention for various embodiments with various modifications as aresuited to the particular use contemplated.

What is claimed is:
 1. A method in a data processing system for transferring data from a plurality of host data links to at least one local data link, the method comprising the steps of: initializing a data bridge, wherein the data bridge is functionally connected on a first end to the plurality of host data links and on a second end to the at least one local data link; determining if a first data link within the plurality of host data links and a second data link within the at least one local data link initiate a login parameter; and automatically transferring the data from a source data link within the first plurality of data links to a target data link within the at least one local data link based on the login parameter.
 2. The method of claim 1, wherein the data transferred from the source link is stored in a memory buffer device.
 3. The method of claim 1, wherein the data bridge is a data link concentrator.
 4. The method of claim 1, wherein initializing the data bridge includes resetting the data bridge.
 5. The method of claim 4, wherein if the data bridge is reset, the plurality of host data links functionally connected to the data bridge and the at least one local data link functionally connected to the data bridge are forced offline by the data bridge.
 6. The method of claim 4, further comprising: monitoring a signal from the first data link within the plurality of host data links and a signal from the second data link within the at least one local data link functionally connected to the data bridge; determining whether an initiating sequence signal is received by the first data link and the second data link; and establishing a data bridge active state if the initiating sequence signal is received by the first data link and the second data link.
 7. The method of claim 6, further comprising: terminating data transfer from the source data link within the plurality of host data links to the target data link within the at least one local data link if the data bridge is in an offline state.
 8. The method of claim 6, further comprising: monitoring the plurality of host data links and the at least one local data link functionally connected to the data bridge; and terminating data transfer from the source data link to the target data link if the plurality of host data links or the at least one local data link does not remain in an active state.
 9. The method of claim 8, wherein if the plurality of host data links and the at least one local data link complete an offline state protocol, the data bridge is reset.
 10. The method of claim 1, wherein the login parameter includes a fibre channel fabric login parameter and a fibre channel port login parameter.
 11. The method of claim 10, wherein the fibre channel login parameter includes buffer credits.
 12. The method of claim 10, wherein the fibre channel port parameter includes a port identification.
 13. The method of claim 1, further comprising: automatically transferring the data from a source data link within the plurality of host data links to a buffer device if the data bridge is in a lockout mode.
 14. An apparatus for transferring data from a plurality of host data links to at least one local data link, comprising: and array of data links; and a data bridge coupled on a first end to the plurality of host data links and on a second end to the at least one local data link, wherein the data bridge is initialized, the data bridge determines if a first data link within the plurality of host data links and a second data link within the at least one local data link initiate a login parameter, and the data bridge automatically transfers the data from a source data link within the plurality of host data links to a target data link within the at least one local data link based on the login parameter.
 15. The apparatus of claim 14, wherein the data transferred from the source link is stored in a memory buffer device.
 16. The apparatus of claim 14, wherein the data bridge is a data link concentrator.
 17. The apparatus of claim 14, wherein initializing the data bridge includes resetting the data bridge.
 18. The apparatus of claim 17, wherein if the data bridge is reset, the plurality of host data links functionally connected to the data bridge and the at lest one local data link functionally connected to the data bridge are forced offline by the data bridge.
 19. The apparatus of claim 17, wherein if the data bridge monitors a signal from the first data link and a signal from the second data link functionally connected to the data bridge, the data bridge determines whether an initiating sequence signal is received by the first data link and the second data link, a data bridge active state is established if the initiating sequence signal is received by the first data link and the second data link.
 20. The apparatus of claim 19, wherein the data bridge terminates data transfer from the source data link to the target data link if the data bridge is in an offline state.
 21. The apparatus of claim 19, wherein the data bridge monitors the plurality of host data links and the at least one local data link functionally connected to the data bridge and the data bridge terminates data transfer from the source data link to the target data link if the plurality of host data links or the at least one local data link does not remain in an active state.
 22. The apparatus of claim 21, wherein if the plurality of host data links and the at least one local data link complete an offline state protocol, the data bridge is reset.
 23. The apparatus of claim 14, wherein the login parameter includes a fibre channel fabric login parameter and a fibre channel port login parameter.
 24. The apparatus of claim 23, wherein the fibre channel login parameter includes buffer credits.
 25. The apparatus of claim 23, wherein the fibre channel port parameter includes a port identification.
 26. The apparatus of claim 14, wherein the data bridge automatically transfers the data from a source data link to a buffer device if the data bridge is in a lockout mode. 